CLU and neoplasm: Some bacterial species, like E. coli, exhibit tropism for tumor tissue, which secretes chemical constituents such as clusterin, TGF-β2, and serglycin, while others, like facultative anaerobes (e.g., Escherichia and Salmonella), can sense the nutrient-rich environment of tumors and contribute to their accumulation in the tumor cells and exert their killing effect [53,54].